1. Field of Invention
This invention relates to home treatment of water and specifically relates to an improved filter element for a gravity-flow water filter.
2. Filter Types and Terms
Pressurized water filters are connected to pressurized water lines. Gravity-flow filters have gravity acting locally as the motive force causing water through flow.
Gravity-flow filters, also called "pour through filters", may generally be described as having a reservoir above a filter body containing a filter medium. Water enters the reservoir, flows downward and then flows through an inlet into the filter body. Water passes through the filter medium and falls into a receiver below the filter body.
Gravity-flow filters usually have lower water pressure at the inlet, lower pressure drop across the filter body, lower flow rates, lesser strength requirements because of low internal pressures, and different physical support than have pressurized filters.
3. A Stability Constraint On Filter Body Height
A gravity-flow filter system may stack reservoir atop filter body atop receiver, with the weight of all resting on the base of the receiver. The taller the filter body, the longer is the water path through the medium and the greater the filtering effectiveness. However, the taller the filter body, the more liable is the stack to tipping and falling. Thus stability considerations place a constraint on the height of the filter body.
3. Description of Prior Art
The filters of U.S. Pat. No. 2,167,225 to Van Eweyk (1939), U.S. Pat. No. 2,224,577 to Shively (1940), U.S. Pat. No. 4,419,235 to Sway (1983), U.S. Pat. No. 3,747,767 to Hankammer (1973), U.S. Pat. No. 4,306,971 to Hankammer (1981), the BRITA.TM. filter (trademark of Brita, Inc., Palisades Park, N.J.), the FILBROOK.TM. filter (trademark of P. B. Enterprises, Woodstock, Vt.) and the Innova.TM. filter (trademark of Innova Pure Water, Inc., Clearwater, Fla.) all use the stack with reservoir atop filter body atop receiver, the weight of all resting on the receiver. Consequently, all these have a serious limitation on filter body height due to the stability constraint.
The filters of U.S. Pat. No. 3,536,197 to S. L. Ward (1970), U.S. Pat. No. 2,033,533 to G. Moore (1936) and U.S. Pat. No. 4,094,779 to Behrman (1978) each utilize a dedicated stand to support various filter parts.
The filters of U.S. Pat. No. 738,486 to Rogers (1903), U.S. Pat. No. 1,774,004 to Haslett (1930) and U.S. Pat. No. 3,529,726 to Keenan (1970) all show watertight connections to a pressurized water source and hence have no gap between source and filter body. Rogers and Haslett show chains which aid in securing the watertight connection.
The devices of U.S. Pat. No. 153,406 to Vaders (1874), U.S. Pat. No. 643,181 to Woodworth (1900) and U.S. Pat. No. 1,028,054 to M. A. Moore (1912) all show mesh screens held in the outflow stream of a water source, but none uses a filter medium. These devices are related to the modern aerator found on the end of most new kitchen and bathroom faucets, which aerator also holds a mesh screen in an outflow.
U.S. Pat. No. 3,385,446 to F. E. Ward et al. (1968) shows a filter device stably supported by being hand held. If more than a quart or so is to be filtered, and if the liquid is to flow through slowly for efficient filtration, then surely holding by hand would be tedious and inconvenient.
The filter of U.S. Pat. No. 3,462,361 to Greenwalt et al. (1969) uses a stopper at the filter body's inlet. No support means is shown for this filter element.
The Innova.TM. filter has a reservoir, filter body and receiver combined in a single unit which is placed under a kitchen faucet for the filtering operation. The device shows no structure to suspend from and position itself under the faucet.
The filter of U.S. Pat. No. 3,715,035 to Teeple et al. (1973) shows a flexible bag reservoir that slumps below the inlet to a filter element. The bag is to be filled with water, and after sediment settles, Teeple provides a structure to elevate part of the bag above the inlet so that water enters the inlet. A receiver bag is attached to the filter body.